Process of conversion of continuous (analog) signals, such as the detected ultrasound or MRI signal (voltage), into numbers. This is carried out with an analog to digital converter.
There are two kinds of discretization involved: the voltage is only measured (sampled) at particular discrete times and only voltages within a particular range and separated by a particular minimum amount can be distinguished. Voltages beyond this range are said to exceed the dynamic range of the digitizer.

(TVR) The transmit voltage response is the level of the acoustic output referenced to one meter per one volt input.

See also Transmit Current Response, Doppler Velocity Signal, Analog Output Signal, and Digital to Analog Converter.

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Amplitude shading is a method of reducing the side lobe levels in a transducer array. The shading usually causes the main beam to broaden by applying different voltages to the elements of the array.

See also Analog Output Signal.